This invention concerns a method for decontaminating chambers used in vacuum processes for deposition, etching and/or growth of high purity films, particularly applicable in semiconductor technology and, specifically, in processes for the deposition, etching and/or growth of films on semiconductor wafers.
In the technology of semiconductor devices, use is preferably made, for deposition, etching or growth of films, of vacuum processes in order to reduce the presence of contaminating substances in the chambers where the processes take place, and consequently to improve the chemico-physical and stoichiometric characteristics of the films obtained. Use is made in particular of systems such as Low Pressure Chemical Vapor Deposition (LPCVD), Plasma Enhanced CVD (PECVD), evaporation, sputtering, Reactive Ion Etching (RIE), systems for etching in plasma, etc.
A known procedure relating to a vacuum process for deposition or etching of films, generally begins with creation of a vacuum in the chamber until a certain minimum pressure level is reached (about 1-25 milliTorr), followed by decontamination of the chamber by allowing non-contaminating gas to flow in at low pressure (e.g. 200 milliTorr) for a previously set time (between 10 and 40 minutes). Then, having once more brought the vacuum down to a certain minimum value, the deposition or the etching processes is begun. Although this method appreciably lessens the presence of undesired gases in the chamber (such as H, H.sub.2, CO.sub.2, OH, H.sub.2 O, etc.) it, however, fails to reduce it below certain desired limits.